Seybert’s Analysis of Chromat of Iron. 323 
# To ascertain whether the proper quantity of acid was 
added to the liquor (E,) a portion of it was rendered slight- 
ly acid, and treated by ammonia ; no precipitate was form- 
ed; it was therefore certain, that the acid added had pre- 
cipitated all the alumine. ‘The liquor was then treated by 
an excess of muriatie acid, it became intensely brown ; chlo- 
rine was disengaged, and on heating the liquor, it was changed 
to a beautiful deep green. The muriatie acid decomposed 
the chromate of potash, and formed muriate of po’ and 
proto-muriate of chrome. e green colour proved that 
the chrome was in the state of a protoxide. The liquor, 
treated by ammonia, yielded a light green precipitate of 
proto-hydrate of chrome, which, washed and calcined, 
gave protoxide of chrome 1.79 grammes on 4.53 grammes 
of the mineral, or 39.514 per 1 
This chromate of iron, after being calcined, is constituted 
Ss. 
as follows. er 100 parts 
C. Silex," + 10.596 Containing oxygen, 5.329 
D, Per-oxide of iron, 36.004 - - - 11.038 
E. Alumine, 13.00 - - - 6.073 
F. Protoxide of Chrome 39.514 - - - 11.810 
| 99.116 
100.000 
000.884 Loss. 
During my residence in Paris, I examined, in the Royal 
School of Mines, a specimen of the chromat of iron, found 
in Chester county, “Potindy Teka: In its external charac- 
ters, it did not vary materially from that found at the Bare 
ills ; the result of the analysis was as follows, viz : 
Per 100 parts. 
Silex, Sis - 02.901 Containing oxygen 01.45 
Peroxide of Iron, - © 35.140 = - - 10. 
Oxide of Manganese, a Trace. 
Alumine, - ~ = - 09.723 - 04.54 
Protoxide of Chrome, 51.562 eek ee ek te 
99.326 
100.000 
000.674 Loss. 
